I took the maximum size I could build, about 4 feet/1.2 meters, multiplied it by 110% to get 54 inches, then I doubled that to 108 inches. If I built a 'prime focus' dish it would be about that large. A focal length (f/d) of 0.68 sounds like you want to build a Ku-Band dish. In a Google search I've found pictures of homemade Ku-Band dishes, they look very flat.

The different angles of the prime focus dish and the offset dish come from the area being used. In the Software and Planning section you see that the offset is a part of the prime focus dish. To imagine the angle, hold up your left hand like you are picking someone up by the waist. Now tilt it up to the sky like a dish and put your thumb from your right hand where the LNB would be. This would represent a prime focus dish, an offset dish would be only the upper half of your left hand (the fingers). It looks like it is pointing down but it is where it needs to be to get the signal. Look at the Elevation picture on this page - http://www.satsig.net/azelhelp.htm - They are both pointed at the same satellite but the offset looks like it is pointed down.

Oval is harder to build, I chose it to prevent the LNB from casting a 'shadow' on the dish and reducing the signal (which might not be an issue). My dish is good near the center but near the top edge it is not perfect, too flat between the ribs. I've noticed that anyone building dishes overseas used the standard round dish. Go to Satbeams.com, click on Footprints to see their recommendation for size of dish per satellite. It gave me an idea of the size I needed to make.

If you mean OTA, I've done that too. We have antennas that I built and use daily (Super Stealth Hawk & Kosmic SuperQuad). We don't have that many channels available by antenna and for a while we were able to supplement our viewing with the satellite dish.

If you mean OTA, I've done that too. We don't have that many channels available by antenna and for a while we were able to supliment our viewung with the satellite dish.